Waterjet cutting systems are used to effect cuts in a variety of materials. For example, U.S. Pat. No. 3,326,607 discloses an apparatus for boring a tunnel through rock by moving a waterjet cutting nozzle around an axis of rotation of a motor. Also, U.S. Pat. Nos. 4,903,559 and 4,966,059 disclose an arc-cutting tool using a waterjet to make arc cuts on an edge of a continuously moving sheet.
It is also known to mount a waterjet cutting nozzle to the end of an articulated arm robot in order to cut large and irregular-shaped holes in sheet material such as plastic panels. Such systems provide a great deal of flexibility in processing panels of different sizes and geometries; and, in addition, adapt well to engineering changes in the product for which the panel is being fabricated.
One limitation of robotic waterjet cutting systems, however, is in the cutting of small circular holes. Typically, robotic waterjet cutting systems are used only in cutting holes having a diameter of more than three-eighths-inch. The reason for this limitation is due to the speed at which a robot controller can process the information needed to coordinate all of its axes of movement to produce a circular path. Generally, to cut a hole using a robotic waterjet cutting system, the robot path speed must be set at about twenty percent (20%) or less of the nominal cutting speed of the waterjet to produce a circular path of acceptable tolerance. Any speed higher than this will produce a hole with an excessive amount of ovality; and the smaller the diameter of the hole to be cut, the worse the ovality condition becomes.
Accordingly, although robotic waterjet cutting systems have significantly improved panel processing speeds where large openings are required, it is not presently feasible to replace traditional drilling methods with waterjet cutting methods in cutting small diameter holes of three-eighths inch or less; and this limitation directly impacts the ability to implement flexible manufacturing techniques utilizing such systems in many applications.